In the two pictures of the woman, I think that the focus is VERY slightly off (hard to get it right with such a thin DOF and low-light). It's possibly backfocussing slightly..

I think it is front focusing based on earrings, scarf, teeth. Not a big deal, my Canon EF primes front focus without MFA dialed in.

Yes, the lens was front focusing rather strongly at zero micro-adjust. I tried to "push it backwards" a bit via micro-adjust (I think I settled on +4 adjustment). However, with only my iPad mini to use on the trip....it was next to impossible to nail the micro-adjustment just right. It probably needed to be pushed back a bit more. By comparison, my 135 2.0L needed +11 and it's very sharp at that setting.

I think I can blame the sharpness problems with the Sigma on me....I'm sure the lens would show much sharper if properly micro-adjusted (and shot in Raw).